Year	Percent change (Units)
1980	2.601
1981	0.610
1982	1.800
1983	1.300
1984	1.400
1985	5.000
1986	3.114
1987	3.300
1988	6.308
1989	4.003
1990	4.324
1991	2.497
1992	3.273
1993	5.048
1994	4.001
1995	4.680
1996	4.462
1997	5.182
1998	3.644
1999	3.812
2000	2.503
2001	3.658
2002	5.165
2003	1.249
2004	2.340
2005	2.997
2006	2.497
2007	6.512
2008	4.142
2009	-1.538
2010	4.219
2011	5.614
2012	5.913
2013	3.946
2014	3.697
2015	3.826
2016	10.821
2017	10.300
2018	6.358
2019	5.617
2020	4.704
2021	5.583
2022	3.972
2023	5.700
2024	4.074
2025	5.600
2026	5.753
2027	5.573
2028	5.642
2029	5.640